diff options
| author | Baoquan He <bhe@redhat.com> | 2020-04-07 05:07:06 +0200 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2020-04-07 19:43:40 +0200 |
| commit | 0a9f9f62316606ee827fa3318e95a1c489d9acf5 (patch) | |
| tree | d27f453193214dc27066da1919693ba7db4b6339 /include | |
| parent | mm/sparse.c: introduce a new function clear_subsection_map() (diff) | |
| download | linux-0a9f9f62316606ee827fa3318e95a1c489d9acf5.tar.xz linux-0a9f9f62316606ee827fa3318e95a1c489d9acf5.zip | |
mm/sparse.c: only use subsection map in VMEMMAP case
Currently, to support subsection aligned memory region adding for pmem,
subsection map is added to track which subsection is present.
However, config ZONE_DEVICE depends on SPARSEMEM_VMEMMAP. It means
subsection map only makes sense when SPARSEMEM_VMEMMAP enabled. For the
classic sparse, it's meaningless. Even worse, it may confuse people when
checking code related to the classic sparse.
About the classic sparse which doesn't support subsection hotplug, Dan
said it's more because the effort and maintenance burden outweighs the
benefit. Besides, the current 64 bit ARCHes all enable
SPARSEMEM_VMEMMAP_ENABLE by default.
Combining the above reasons, no need to provide subsection map and the
relevant handling for the classic sparse. Let's remove them.
Signed-off-by: Baoquan He <bhe@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Cc: Wei Yang <richard.weiyang@gmail.com>
Link: http://lkml.kernel.org/r/20200312124414.439-4-bhe@redhat.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/mmzone.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index 42b77d3b68e8..f3f264826423 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -1143,7 +1143,9 @@ static inline unsigned long section_nr_to_pfn(unsigned long sec) #define SUBSECTION_ALIGN_DOWN(pfn) ((pfn) & PAGE_SUBSECTION_MASK) struct mem_section_usage { +#ifdef CONFIG_SPARSEMEM_VMEMMAP DECLARE_BITMAP(subsection_map, SUBSECTIONS_PER_SECTION); +#endif /* See declaration of similar field in struct zone */ unsigned long pageblock_flags[0]; }; |